package cn.com.dev;

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.Serializable;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;

public class HttpPostEmulator {
    // 每个post参数之间的分隔。随意设定，只要不会和其他的字符串重复即可。
    private static final String BOUNDARY = "----------HV2ymHFg03ehbqgZCaKO6jyH";

    public String sendHttpPostRequest(String serverUrl, ArrayList<FormFieldKeyValuePair> generalFormFields, ArrayList<UploadFileItem> filesToBeUploaded) throws Exception {

        // 向服务器发送post请求

        URL url = new URL(serverUrl/* "http://127.0.0.1:8080/test/upload" */);

        HttpURLConnection connection = (HttpURLConnection) url.openConnection();

        // 发送POST请求必须设置如下两行

        connection.setDoOutput(true);
        connection.setDoInput(true);
        connection.setUseCaches(false);
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Connection", "Keep-Alive");
        connection.setRequestProperty("Charset", "UTF-8");
        connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + BOUNDARY);

        // 头
        String boundary = BOUNDARY;

        // 传输内容
        StringBuffer contentBody = new StringBuffer("--" + BOUNDARY);

        // 尾
        String endBoundary = "\r\n--" + boundary + "--\r\n";

        OutputStream out = connection.getOutputStream();

        // 1. 处理文字形式的POST请求
        for (FormFieldKeyValuePair ffkvp : generalFormFields) {
            contentBody.append("\r\n")
                    .append("Content-Disposition: form-data; name=\"")
                    .append(ffkvp.getKey() + "\"")
                    .append("\r\n")
                    .append("\r\n")
                    .append(ffkvp.getValue())
                    .append("\r\n")
                    .append("--")
                    .append(boundary);
        }

        String boundaryMessage1 = contentBody.toString();
        out.write(boundaryMessage1.getBytes("utf-8"));

        // 2. 处理文件上传
        for (UploadFileItem ufi : filesToBeUploaded) {
            contentBody = new StringBuffer();
            contentBody.append("\r\n")
                    .append("Content-Disposition:form-data; name=\"")
                    .append(ufi.getFormFieldName() + "\"; ") // form中field的名称
                    .append("filename=\"")
                    .append(ufi.getFileName() + "\"") // 上传文件的文件名，包括目录
                    .append("\r\n")
                    .append("Content-Type:application/octet-stream")
                    .append("\r\n\r\n");

            String boundaryMessage2 = contentBody.toString();
            out.write(boundaryMessage2.getBytes("utf-8"));

            // 开始真正向服务器写文件
            File file = new File(ufi.getFileName());
            DataInputStream dis = new DataInputStream(new FileInputStream(file));
            int bytes = 0;
            byte[] bufferOut = new byte[(int) file.length()];
            bytes = dis.read(bufferOut);
            out.write(bufferOut, 0, bytes);

            dis.close();

            contentBody.append("------------HV2ymHFg03ehbqgZCaKO6jyH");
            String boundaryMessage = contentBody.toString();
            out.write(boundaryMessage.getBytes("utf-8"));
            System.out.println(boundaryMessage);

        }

        out.write("------------HV2ymHFg03ehbqgZCaKO6jyH--\r\n".getBytes("UTF-8"));

        // 3. 写结尾
        out.write(endBoundary.getBytes("utf-8"));
        out.flush();
        out.close();

        // 4. 从服务器获得回答的内容
        String strLine = "";
        String strResponse = "";
        InputStream in = connection.getInputStream();
        BufferedReader reader = new BufferedReader(new InputStreamReader(in));

        while ((strLine = reader.readLine()) != null) {
            strResponse += strLine + "\n";
        }

        System.out.print(strResponse);
        return strResponse;

    }

}